Question

Focal length of a thin convex lens is 30 cm. At a distance of 10 cm from the lens, there is a plane refracting surface of refractive index $\frac{3}{2}$. A parallel beam of monochromatic light rays incident on the lens, then they converge at a distance of

• A. 60 cm from the lens
• B. 50 cm from the lens
• C. 45 cm from the lens
• D. 40 cm from the lens

Answer 1

The correct option is D

40 cm from the lens

\(\frac{1}{y}=\frac{\frac{3}{2}}{20} \Rightarrow y=30\)
$I_2$ will be formed 40 cm from the lens.